Active noise control (ANC) systems are used in many vehicle exhaust systems to control the level of sound emitted by the exhaust system. Integrating an ANC system into a vehicle exhaust system is an attractive way to achieve a lower weight in a smaller packaging area, and can provide a system that can potentially out-perform traditional exhaust systems in terms of back pressure and tailpipe noise reduction. Additionally ANC systems are beneficial because they can add noise as well as cancel noise.
Noise attenuation difficulties arise for controlling low frequency noise, such as noise below 80 HZ, for example. To effectively cancel low frequency noise, a very large speaker diameter with a significantly large back volume, e.g. an increase from 3.5 L to 16 L, is required in order to effectively reduce or cancel the exhaust sound. Also, a significant amount of speaker power and/or more than one speaker may be required in order to sufficiently address all desired noise levels. This disadvantageously requires a significant amount of packaging space, and also increases cost and weight. Additionally, this causes even further issues when there is a dual tailpipe configuration.